1. Field of the Invention
This invention relates to new and improved circuit breakers and, in particular, to circuit breakers utilizing an integrated power-trip arm. Accordingly, it is a general object of this invention to provide new and improved devices of such character.
2. Description of the Prior Art
In a residential type circuit breaker of the prior art, it had been the common practice to utilize a connector that was mounted in an insulated housing. The connector was adapted to engage a line bus when the breaker was inserted into a distribution panel box. A fixed contact was affixed to the connector. A movable handle, which had a slot therein, was mounted in the housing. An actuator plate, pivotable about a fixed point on the housing, had a leg for pivotal engagement within the slot. The plate had a boss protruding perpendicular to its otherwise planar body. A movable contact carrier had a pivotal point of connection at one end thereof. A contact was provided at the opposite end thereof for movable engagement with and disengagement from the fixed contact. A first end of a slotted plate was adapted to pivot within an indentation of the housing. An opposite end of the plate was adapted to pivotally engage with the pivotal point of connection. The slotted plate was provided with a slot which received the boss. A trip arm had one end thereof adapted to pivot about a pivot axis of the housing and had a portion thereof adapted to engage an overcenter tension spring that was coupled between the portion and a point on the contact carrier other than the pivotal point. A biasing tension spring was coupled between the contact carrier and the leg on the actuator plate. A latch was provided which was pivotable about a second pivot axis of the housing. The latch had a pair of latching extremities and had a limiting portion to limit extent of rotation in one direction. One of the latching extremities was adapted to engage with the latching end of the trip arm. A load terminal included means for a load conductor to be coupled to the circuit breaker. A thermally responsive latching member had one end coupled to the load terminal and had an opposing end adapted to engage the other of the latching extremities of the latch. A flexible conductor conductively connected the contact carrier to the latching member.
Disadvantageously, the foregoing prior art circuit breaker would occasionally result in the contacts being welded together. Obviously, the welding of circuit breaker contacts to each other is undesirable, unreliable, and hazardous. The welding of the circuit breaker contacts to each other could be avoided by an increase in power that was used in the circuit breaker, but such increased use of power is expensive.
More recently, a circuit breaker having similar elements was provided wherein the breaker was initially reset by moving the handle in one direction, pushing the trip arm into a latch. In turn, the latch got engaged by the bimetal thermostatic element. When the bimetal thermostatic element got overheated and deflected, it released the latch which, in turn, released the trip arm. The trip arm, then, impacted a separate power arm, a small device which then, in turn, impacted the moving arm. Disadvantageously, however, the extra power arm, being an extra piece, provided increased cost in both the producing and the mounting of same. The extra piece had an inherent short life. The mounting of the extra piece slowed production compared to the previous device by approximately eight percent.
With the instant invention, production rates equal to what they were, prior to the separate power arm, are achievable.